Apparently, this is something that pisses off women – when men tell them to smile.
Strangely, I can sympathize. I’m a man but apparently my face is quite angry and/or unhappy looking because at least once a week, some random doofus will say something to me like, “Hey, smile! It’s not so bad!” or “Wow, you look thrilled today!” or some such nonsense.
Usually, I just let it pass but once in awhile I get annoyed and say something like, “I don’t know what you want from me. Am I supposed to be dancing a jig and laughing like a clown 24/7?”
It’s stupid. Most people don’t run around with a smile like the Joker all the time.
I think when men do this to women it is just a lame pickup line. They can’t think of anything else to say and are probably too dumb to realize that they are saying because the woman isn’t smiling at that precise moment she must be a raging bitch or something.
I don’t know why people do it to me though. Am I the only man this happens to? I must be a real depressed looking bastard.
Anyway, there was a scene in Captain Marvel where a random dingus tells her to smile and she responds by swiping his bike. It made me think of my own tribulations with this tomfoolery.
Bookshelf Battle 
Some people just have RBF. He’s madly tall, intensely introverted (doesn’t talk to people), and has a mean looking face. I warn the folks at the coop when my hubs takes my kiddo for me. Just so they don’t call the police. “Yes, huge angry man around children, come quick!”